(a) Technical Field of the Invention
This invention is related to a mechanism which is arranged in an overfill prevention device and used for controlling a gauge for indicating the amount of gas remaining in a gas tank.
(b) Description of the Prior Art
Combustible liquefied gas is convenient for us to carry out combustion operation, and especially as liquefied gas burns completely The burning is very clean, and unlike coal, no black smoke will be produced. Hence, liquefied gas is widely used for heating, and cooking. Further, liquefied gas is also used for welding and manufacturing. However, no matter what kind of liquefied gas is used, they must all be filled in a gas tank in order to facilitate their transportation. When in use, the outlet of the gas tank is connected to the gas appliance, so that when the gas tank valve is turned on, the liquefied gas will flow to the burner of the gas appliance for burning.
Generally, the conventional gas tank is provided with a simple valve. When the liquefied gas is decreased to a level such that it is insufficient for cooking a meal, the user cannot perceive this, so that it often happens that cooking will be interrupted as a result. Thus, the user has to purchase a new gas tank or refilling gas in order to continue cooking, which is inconvenient, particularly for people located far from gas stations or the like. However, it is also dangerous to have multiple gas tanks in the home.
Schmitz et al (U.S. Pat. No. 7,219,686) discloses a tap assembly for a liquid vessel having an overfill protection device and a float controlled magnetic level gauge, wherein, a crank mechanism is provided between the float lever and the rod of the level gauge to cause the rod to effectuate a swinging movement and simultaneously displace the rod longitudinally to cause linear displacement of the permanent magnet in the valve body bore. However, since the rod is driven in a swinging movement, the upper end of the rod would be easily stuck thereby making it unfit for practical use.
Lundquist (U.S. Pat. No. 1,456,701) discloses a liquid level gage which comprises in combination a vertically movable indicator member, a flexible wire attached directly thereto, a float and float-actuated means operated by the upward movement of the float and connected directly to the other end of the wire for exerting a pull upon the wire and lowering the indicator member. Nevertheless, the Lundquist reference is designed for use with gasoline or diesel in which the buoyancy of a float is approximately 3˜4 times as much as that in a liquefied gas. Hence, the Lundquist reference is workable in gasoline or diesel, but it would not be workable to apply such a high friction mechanism to be used in liquefied gas where the buoyancy received by the float is small.
Therefore, it is an object of the present invention to provide an overfill prevention device with a gauge for indicating the amount of gas remaining a gas tank which can obviate and mitigate the above-mentioned drawbacks.